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AD633
Data Sheet
Rev. J | Page 10 of 20
Likewise,
Figure 16 shows how to implement a divider using a
multiplier in a feedback loop. The transfer function for the
divider is
( )
X
E
V
W
10
=
′
(6)
AD633JN
X1
1
X2
2
Y1
3
Y2
4
+VS 8
W
7
Z
6
–VS 5
0.1F
+15V
0.1F
+15V
0.1F
–15V
00786-
015
7
4
3
6
2
AD711
E
R
10k
R
10k
EX
W' = –10V
E
EX
Figure 16. Connections for Division
VARIABLE SCALE FACTOR
In some instances, it may be desirable to use a scaling voltage
other than 10 V. The connections shown i
n Figure 17 increase
the gain of the system by the ratio (R1 + R2)/R1. This ratio is
limited to 100 in practical applications. The summing input, S,
can be used to add an additional signal to the output, or it can
be grounded.
AD633JN
X1
1
X2
2
Y1
3
Y2
4
+VS 8
W
7
Z
6
–VS 5
0.1F
+15V
–15V
W =
00786-
016
S
R1
R2
1k ≤ R1, R2 ≤ 100k
+ S
(X1 – X2)(Y1 – Y2)
10V
R1 + R2
R1
X
INPUT
Y
INPUT
+
–
+
–
Figure 17. Connections for Variable Scale Factor
CURRENT OUTPUT
The voltage output of the
AD633 can be converted to a current
output by the addition of a resistor, R, between the W and Z pins of
AD633JN
X1
1
X2
2
Y1
3
Y2
4
+VS 8
W
7
Z
6
–VS 5
0.1F
+15V
–15V
IO =
1
R
00786-
017
(X1 – X2)(Y1 – Y2)
10V
1k ≤ R ≤ 100k
R
X
INPUT
Y
INPUT
+
–
+
–
Figure 18. Current Output Connections
This arrangement forms the basis of voltage-controlled integrators
and oscillators as is shown later in this section. The transfer
function of this circuit has the form
(
)(
)
V
Y2
Y1
X2
X1
R
IO
10
1
=
(7)
LINEAR AMPLITUDE MODULATOR
T
he AD633 can be used as a linear amplitude modulator with no
external components
. Figure 19 shows the circuit. The carrier
and modulation inputs to the
AD633 are multiplied to produce
a double sideband signal. The carrier signal is fed forward to the
Z input of th
e AD633 where it is summed with the double
sideband signal to produce a double sideband with the carrier
output.
AD633JN
X1
MODULATION
INPUT
±EM
CARRIER
INPUT
EC sin ωt
1
X2
2
Y1
3
Y2
4
+VS 8
W
7
Z
6
–VS 5
+
–
0.1F
+15V
–15V
W =
EC sin ωt
00786-
018
EM
10V
1+
Figure 19. Linear Amplitude Modulator
VOLTAGE-CONTROLLED, LOW-PASS AND HIGH-
PASS FILTERS
Figure 20 shows a single multiplier used to build a voltage-
controlled, low-pass filter. The voltage at Output A is a result
of filtering ES. The break frequency is modulated by EC, the control
input. The break frequency, f2, equals
)
2
(
10
RC
E
f
C
2
π
=
(8)
and the roll-off is 6 dB per octave. This output, which is at a
high impedance point, may need to be buffered.
AD633JN
X1
1
X2
2
Y1
3
Y2
4
+VS 8
W
7
Z
6
–VS 5
CONTROL
INPUT EC
SIGNAL
INPUT ES
0.1F
+15V
–15V
00786-
019
R
C
1 + T1P
1 + T2P
OUTPUT B =
1
1 + T2P
OUTPUT A =
1
ω1
T1 =
= RC
1
ω2
10RC
EC
T2 =
=
dB
f2 f1
f
–6dB/OCTAVE
OUTPUT A
OUTPUT B
0
Figure 20. Voltage-Controlled, Low-Pass Filter
The voltage at Output B, the direct output of th
e AD633, has the
same response up to frequency f1, the natural breakpoint of RC
filter, and then levels off to a constant attenuation of f1/f2 = 10/EC
RC
f
π
=
2
1
(9)